Feedbox transmission for lathes



June 2, 1953 w. G. HOELSCHER 2,640,369

FEEDBOX TRANSMISSION FOR LATHES Filed Sept. 8, 1948 7 Sheets-Sheet vl j3 Q o .1

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June 2, 1953 w. e. HOELSCHER 2,640,359

FEEDBOX TRANSMISSION FOR LATHES Filed Sept. 8. 1948 7 Sheets-Sheet 2 INV EN TOR. TQ 1 M A R YS.

June 2, 1953 w. G. HOELSCHER 2,640,369

FEEDBOX TRANSMISSION FOR LATHES Filed Sept. 8, 1948 TSheets-Sheet s wINVENTOR. 7: l, m1, HMW

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June 2, 1953 w. G. HOELSCHER 2,640,369

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June 2, 1953 ,w. e. HOELSCHER FEEDBOX TRANSMISSION FOR LATHES 7Sheets-Sheet '7 Filed Sept. 8. 1948 A Tm 77/05? a L I INVENTOR. A HM wknW Patented June 2, 1953 UNITED STATES PATENT OFFICE 2,640,369 7 FEEDBOXTRANSMISSION FOR LATHES William G. Hoelsche'r, Cincinnati, Ohio,assignor to The American Tool Works Company, Cincinnati, Ohio, acorporation of Ohio Aptlioajtion September s, 1948, Serial No. 48,244

3 Claims.

This invention relates generall to lathes and is particularly directedto improvements in the structure of the variable speed feed box whichdetermines the longitudinal feed rate or the lathe carriage. The presentstructure is of the tumbler gear type which embodies a cone or multiplediameter speed gears and a tumbler unit which may be shifted bothlongitudinally and transverse 1y in an arc to establish a meshingengagement with the selected cone gear. A feed box of this nature isdisclosed in the prior patent of William G. Hoelscher, NO. 1,982,612,issued November 27, 1934. The present feed box follows generally theprinciples disclosed in the prior patent and is designed to provide asimplified structure which provides improved performance and easier,more convenient selectivity.

In general, the feed box is of the invertible drive type by means ofwhich two separate speed ranges are provided by a simple change in thegear train so that the feed box may selectively he converted either forcutting threads according to the American standard system or accordingto the metric system. This conversion is accomplished by the use of adetachable input gear which may be selectively placed on either of apair of shafts so that in one instance the input drive is from thetumbler unit to the cone gears and in the second. instance from the conegears to the tumbler unit. This arrangement provides a dual set ofspeeds utilizing the same gears in both instances by reason of the factthat when the drive is inverted or transposed, the ratio of the drive tothe driven gears likewise is ihverted in the present dlsclcsiire, thecone gear and tumbler provides ten speeds and the transmissionadditionally is equipped with two secondary range adjustment gear sets,one or which pro vides two changes and the other three. The transmissionthus provides sixty feed rates for the various American standard threadsand sixty feed rates for metric threads. Power from the feed box istransmitted selectively either to a feed rod or to a lead screw whichextends from the feed hex lengthwise of the lathe bed. The carriage isarranged to be actuated selectively by therod or lead screw according"to the type of work.

The tumbler unit constitutes a swinging memher which is slidably splinedupon one of the transmission shafts and carries a gear at its swingingend adapted to mesh with the selected ear of the cone. The unit isadjusted by means of two manual selector devises. One 'of these shiftsthe unit longitudinally relative to the gear the other swings thetumbler in an are relative to the shaft for meshin it with theseleote'cleear.

One of the rimary objects or the resent invention has been to provide a-sil'l'llflifieii attuating 'lnechailism for the tumbler unit whichpermits the tumbler to be shifted relative to its component gear conesmoothly, quickly and with very little resistance. For this purpose thetumbler l-lhlt is maintained in a vertical position relative to itsmounting shaft, substantially in balance so that its swinging movementsare virtually ullaff-fited by gravit thus providing exceptional ease ofadjustment. The tumbler unit is provided with teeth slidably meshindirectly with a rotatable toothed shaft or elon ated gear so that intermeaiate arts are eliminatedano lost motion t e to wear is greatlyreduced. By providing a yoke connection to the tumbler closely relatedto the shaft upon whioh'th'e tumbler unit is translated longitudinallyand opposite to its toothed ehd, frictional losses and the tendency forthe unit to bind relative to its mounting Shaft is avoided. therebyimproving the slidabilit'y of the unit, pro= viding ease and accuracy ofadj stment. '7 Y Another object has been to provide a simplifiedstructure to permit changing the range or speeds provided by the coneand tumbler by the use of independently shiftable range shift 'gears ahdcontrol levers such that the various ranges may be selected by actuatingeither or both levers to select diretly the desired range withoutprogrossing through the entire series of ran es. This provides greaterspeed in selection and avoids the dlfiiclllty of meshing and unmeslllngseries of gears to reach the desired combination.

Still another object has been to provide simian: fled and direct actingcontrol apparatus for shifting the secondary range adjustment gears andan improved selector to couple the feed rod and laid screw to the feedbox gear train. Further objects and salient features of the inventionare more fully disclosed in the fc'allow n detailed descriptionreferehoe to the drawings which disclose a preferred emtodiiherlt of theinvention.

In the drawings: Figure 1 is a geheral elevation illustrating alatheequipped with improved feed oontrol unit.

Figure 2 is enlarged side elevation of the feed control unitillustrating the various control levers associated therewith.

Figure 3 is end view further illustrating the general arrangement of thefees control Figure 4 diseloses the unit is viewed from the stock and atail stock I1.

end opposite to that shown in Figure 3, illustrating the gear train bywhich the power is transmitted from the head stock to the feed controlunit.

Figure 5 is a sectional view taken on line 5-5, Figure 3, illustratinggenerally the gear train and speed change apparatus of the control unit.

Figure 6 is a sectional view taken on line 55, Figure 5, detailing theshifter mechanism for selectively coupling the feed rod or lead screw tothe feed box gear train.

Figure 7 is a sectional View taken on line 'I---(, Figure 5, detailingthe shifter mechanism for one of the range selectors.

Figure 8 is a sectional view taken on line 8-8, Figure 5, detailing thecontrol mechanism for the tumbler gear unit.

Figure 9 is a sectional view taken on line 99, Figure 5, furtherillustrating the structure and arrangement of the speed change tumblerand its actuating mechanism.

Figure 10 is a general layout of the speed change gearing with thevarious shafts and gears shown in a common plane for convenience ofillustration, with the shiftable gears in a neutral position and thetransmission system set up for speed ranges suitable for the Americanstandard threads.

Figure 11 is a diagrammatic view illustrating a development of the geartrain similar to that shown in Figure 10, but showing the detachableinput gear shifted to a position for operating the driving transmissionat speeds suitable for metric threads.

Referring to Figure 1, which illustrates a lathe equipped with thepresent feed box structure, the assembly embodies a lathe bed i5 havinga head A carriage I3 is slidably mounted on the bed and a lead screw 2Band feed rod 2i extend along the front of the bed in the usual manner,in driving connection with the carriage. For this purpose the carriageis equipped with asplit nut, engageable by means of the lever 22, withthe lead screw 20. The carriage includes also a gear train which is inkeyed or splined connection with the feed rod 2! and in drivingconnection with the rack 23 which is secured to the upper portion of thebed. A control lever 24 is in operating connection with the gear trainto drive the carriage in either direction by power from the feed rod.The feed rod and lead screw are selectively driven by means of the feedbox indicated generally at 25 which is mounted upon the head stock It.The feed box is provided with a gear train having shiftable gears bymeans of which the speed of the lead screw or feed rod may becontrolled.

Described generally with reference to Figure 4, the feed box is drivenby means of a set of gears at the rearward end of the head stock so thatcarriage speed is correlated to spindle speed. Since the head stockforms no part of this invention, .the' details of its construction areomitted except so much of it as is necessary to drive-the feed box. Asshown, the head stock transmission includes a shaft 26 which extendsbeyond the end wall of the head stock. A gear 21 is keyed to this shaftand meshes with an idler gear 28 loosely journalled on a stub shaft 30.,fixed upon a swinging quadrant 3i which is lockedby means of a bolt 32.Gear 28 meshes with a gear 33 which forms-a part of the feed box geartrain. The quadrant is rotatably mounted on the shaft 26 and its lowerend includes a slot 3t which is traversed by the bolt 4 32. The shaft 30of idler gear 28 preferably is fixed in a slot 29 to permit the shaft 30to be shifted relative to the quadrant in order to change gear 28 forspeed variation.

Arrangement of gear train As illustrated in Figure 10, gear 33, which isdriven by the head stock transmission, is mounted upon a shaft 35 whichis journalled on ball bearings 3536 mounted in the end wall 3! of thefeed box '25. The gear is keyed as at 38 to a sleeve 40 which is keyedto shaft 35, and is secured against displacement by means of a nut 4!which is screwthreaded to the sleeve 4!). A gear 42 is keyed upon theinner end of shaft 35 and gear 42 meshes with an idler gear 43journalled on ball bearings 44 upon a stub shaft 45. Gear 43 meshes witha gear 48 which includes a sleeve 41. A sleeve i8 is telescopicallyengaged over and keyed to sleeve 41 and includes a gear 50 which isdisposed to the outside of casing 25. Gears 46 and 50 are looselyjournalled on bearings 5| mounted upon the bearing end of splined shaft52 so that the gears rotate loosely as a unit relative to the shaft.

As shown in Figure 10, in which the unit is arranged for Americanstandard thread feeds, gear 50 meshes with gear 53 which is keyed to theend of splined shaft 54. It is to be noted at this point that gear 53 isdetachably mounted upon shaft 54 by means of the nut 55 so that gear 53may be detached and placed upon the end of shaft 55 to convert thetransmission for metric thread feeds as hereinafter described.

The drive from gear 53 is transmitted to shaft 54 and to gear 56 whichis slidably splined to shaft 55 and forms part of the shiftable tumblerunit indicated generally at 5?. Gear 56 meshes with a gear 58 which iscarried upon a stub shaft 50 mounted on ball bearing Bl formed in theswinging end of the tumbler unit 511'. As shown in Figure 9, gear 58 isadapted to mesh selectively with any one of the gears 62 of the cone ofgears generally indicated at 53. These gears are keyed to shaft 56 whichis loosely journalled upon ball bearings 55 mounted in the opposite endwalls of the feed box. Shaft 55 includes a shiftable clutch element 55which is slidably engaged upon the splined end 56 of the shaft. Theteeth 61 of clutch element 65 mesh with cooperating teeth formed on theend of a pinion 38 as a part of compound gear 59, which includesincludes a gear 10. The compound gear is journalled upon ball bearings Hand 12 mounted respectively in the casing wall and on shaft 56, so thatthe unit is free to rotate relative to the shaft 56. This gear andpinion unit is held against endwise displacement by means of a shoulderscrew l4 engaged in the end wall of the casing, with its inner end inabutment with the face of gear 10. The pinion 58 and gear H3 are adaptedto establish a driving connection selectively with a shiftable compoundgear and pinion unit l5 slidably mounted upon the splined shaft 52. Whenthe unit is shifted to the left, the gear 16 of the unit meshes withpinion 68 and when the unit is shifted to the right, the pinion TImeshes with gear ill. The shiftable gear and pinion 15 isshifted bymeans of a range control lever at the front of casing 25 (Figure 2), ashereinafter described in greater detail.

Upon splined shaft 52 is pinned a gear 8! and compound gear 82 having apinion 83 and a gear 84. A mating compound gear 85 is slidablya uopeemounted upon a splined shaft 36 which is journalled in ball bearings 82.Compound gear 85 includes a pinion 88 adapted to mesh with gear 81, agear 89 adapted to mesh with pinion B3 and a gear 90 adapted to meshwith gear 84 to provide a selection of three speed ranges in addition tothe two speed ranges provided by the compound gear l5 noted above.Compound gear 85 is shifted by means of a three position actuating lever94 mounted on the feed box as shown in Figure 2. From the shaft 86, thedrive is transmitted either to the lead screw 20 or the feed rod 2!. Forthis purpose a slidable pinion and clutch unit 92 is carried upon thesplined end 93 of shaft 86. A pinion 94 of this unit is adapted to meshwith a gear 95 having clutch teeth 96 engaged with the teeth of a collar91 which is pinned to the feed rod 25. The clutch teeth 98 of the unit92 are engageahle with clutch teeth formed on a collar 99 which ispinned to the end of the lead screw 2' Clutch unit 92 is shifted bymeans of a control lever Hill journalled in the feed box adjacent lever(it. It will be apparent that this arrangement provides for establishinga selective driving connection either with the lead screw 2% or with thefeed rod 2! depending upon the position of lever loll. In summary, thegear train is established from gears 33 and 52 to idler gear is whichmeshes with gear '36 to drive the component gear Elil, which meshes withthe gear Gear 53 drives shaft 54 and gears 56 and 58 of the tumbler unitto transmit the drive to the gears 52 of the cone 63. Rotation of thegears 82 is transmitted through shaft 56 to clutch unit 55, to pinionlit and gear H! of compound gear at, to the shiftable compound gear '55on shaft 52. rom shaft 52 the power is transmitted to shaft 86 by of theshiftable compound gear unit 85 and from the splined end of shaft 36either to the lead screw or to the feed rod.

Inverse gear train When the feed box is converted to metric operation,the gear 53 is removed from shaft 54 and placed upon shaft 56 as shownFigure 11. In this instance the drive is established from gear 33 togear 42 to idler ts to the component gears 16 and 50. Gear 58 mesheswith gear 53 which is now keyed directly to shaft 59 to drive the cone63. From cone E3, the power is transmitted through the tumbler unit 57to shaft 55 instead of driving from the tumbler to cone 63 as previouslydescribed. This changes the entire gear ratio since the cone gears whichpreviously were driven now become the driving gears. It is to be notedat this point that the end of shaft 55 includes a loosely journalledcompound gear unit 69a, duplicating compound gear til, and includ ing ashiftable clutch collar 85a similar to the clutch collar 65 abovedescribed. These respective clutch collars are connected to a shifterI!!! which is operated by a selector lever E92 (Figure 5). When the feedbox is converted into metric operation, lever W2 is shifted from theposition shown in Figure 5 so that the position of the clutch collars isreversed.

As shown in Figure 7, the shiftable compound gear 75 is arranged to meshboth with the compound gear 59, and 69a. Thus, when the cornpound gear590. is coupled to shaft 5%, compound gear 69 will idle and the drivewill be transmitted from shaft o l to shaft 52 by the shiftable compoundgear i5. It will be apparent therefore, that the shiftable compoundgears 6 15 and operate in the same manner when the drive is inverted sothat six range changes may be made by shifting the levers "8D and 91.From the shaft 86 power is transmitted to the lead screw and feed rod inthe same manner as previously described.

From the foregoing, it will be observed that with the transposable inputgear 53 in the position shown in Figure 10; the power is transmittedfrom "the tumbler unit 5! to the cone 63 while in the position shown inFigure 11, the power is transmitted from the cone to the tumbler unit,thus alternating the drive so that an entirely new series of speedranges is established.

Control linkage for the ramge control levers and selector lever As shownin Figures 5 and 6., the apparatus for coupling the lead screw or feedrod to the feed box is actuated by the previously noted selec tor lever10%]. This lever includes a detent M3 to latch it in its selectedpositions. The lever is keyed to shaft HM journailed in the feed boxcasing and having a shifter lever m5 keyed to its inner end. A shifterfork lilo is slidably mounted upon rods l'll'll07 and has its inner endpivotally connected to lever [65. The outer end of fork its engages agroove I08 (Figure 10) formed in the clutch and pinion unit 92. Thus,the lever in one position couples the clutch teeth to the lead screw,while in its second position the gear 9% meshes with gear '95 to drivethe feed rod with the lead screw clutch teeth disengaged. The movementlimits of this lever are indicated in Figure 2.

The range selector lever 88 is illustrated in Figures 5 and '7. As shownin Figure 7, the lever is secured upon the end of shaft Hi3 journ'alledin the feed box casingand following the construction of lever I09previously disclosed. To the inner end of shaft Hi) is keyed a gearsegment HI meshing with a rack H2. Rack H2 is secured to a slider I Itwhich is slidably mounted upon the rods ll4--I Hi. A yoke H5 extendsupwardly from slider H3 and engages the opposite sides of the gear 16 ofcompound gear 75. Swinging movements of lever Sill therefore cause theslider and yoke to shift the compound gear either into mesh with thepinions 53 or the gears m to change the speed range of the transmission.The two positions of this lever are shown in Figure 2. 4 The lever 9|for shifting the compound gear 85 is substantially a duplicate of lever80 with the exception, that lever 9! has three gear meshing positionsinstead of two, as in the case of lever 80. As shown in Figures 5 and 9,lever 81 is keyed to a shaft H6 having a gear segment ill keyed to itsinner end in mesh with a rack H8 secured to a slider 12!? carried by therods H4 previously noted. A yoke arm IN forms a part of slider ml andengages the gear 89 of the slid'able compound gear 85. Shiftingmovements of lever Ell selectively meshes shiftable gear 90 with gear88, gear 39 with gear 83 or pinion 88 with gear 3l, as previously noted.

The transfer lever H32, which is actuated to convert the transmissionfrom American standard to metric thread cutting, is mounted upon a shaftI22 as shown in Figure 5. The swinging end of lever I02 includes a pinI23 engageable selectively with either of a pair of apertures H t-I2(Figure 3) to lock the lever in a selected position. Pin I23 is'screwthreaded into the arm 102 so that it is necessary to unscrew thepin and disengage the stud I25 from the apertures I24 before shiftingthe arm. The inner end of shaft I22 is provided with a screwthreadedportion I2! which is in screwthreaded engagement with a slider I28(Figure 'l') which is pinned to a slide rod I33. The opposite end ofslider I28 carries a pin I3I engaged in a slot in the upper end of thelink IEBI which is centrally pivoted upon a shoulder screw I32 inscrewthreaded engagement with a lug I33 forming a part of the feed boxcasing. The screwthreaded portion I2? is of multiple pitch so that apartial turn of lever I02 is sufficient to swing the lever IilI asufficient distance to couple and uncouple alternately the clutches 65and 35a.

Tumbler shifting apparatus The tumbler unit 51 is shiftablelongitudinally in order to mesh with the respective cone gears 62 and isshiftable also transversely in an are relative to these gears so that aproper meshing engagement between the tumbler gear 53 and the respectivegears 62 may be established. As shown in Figure 2, a lever I33 isprovided at the front of the feed box for shifting the tumbler in an arctransversely relative to the cone gears 62. This lever swings relativeto a sector I35 having a series of apertures I3! engageable by means ofa spring loaded plunger I38 mounted in the swinging end of lever I35.Plunger I38 includes a handle I33 at its outer end. A compression springI43 surrounds the shank of the plunger to urge the same into latchingengagement with the apertures I31. The inner end of lever I35 is pinnedupon a sleeve MI, the inner end of which includes a gear M2 (Figure 8).Gear I42 meshes with idler I43 journalled upon idler shaft I44 which ismounted in the feed box casing 25. Idler I43 meshes with a gear I45formed on the hub or a bevel gear I46 which meshes with a bevel gear M!keyed upon the end of a shaft or elongated gear I 48 having its opposite ends journalled as at I53I3il in the easing 25.

As shown in Figures 9 and 10, the tumbler unit 51 constitutes a sectoriI which is provided with a bore having a pair of ball bearings I52I52to provide a pivotal connection upon the hub I53 of gear 53. The sectoris milled out centrally to provide clearance for the gears 56 and 58 andprovides a bore to receive the ball bearings EI-6l of idler shaft 38.The upper or swinging end of the sector is provided with gear teeth I5!meshing with the teeth I58 formed lengthwise of shaft I48. It will beapparent therefore, that rotation of the actuating lever I35 toward theleft will drive the shaft I48 in an appropriate direction to cause thetumbler unit 51 to swing to the right as viewed in Figure 9 so that gear58 swings clear of the largest gear on cone 63. It will be noted inFigure 9 that the sector is mounted in a vertical position upon itssplined mounting shaft 54, substantially in a balanced condition. Thisreduces materially the effort exerted by the operator in shifting thesector because it swings relative to a neutral or balanced position withmost of its weight imposed on shaft 54.

It will be noted also, that there is a set of ten gears 52 in the conegear and that there are ten apertures I31 in the sector I36. Theseapertures lock the gear 58 in proper meshing engagement with the conegears 62. A notched rod I59 cooperates with a lug 63 formed on thesector to prevent longitudinal displacement of the 8 sector whenit is inmesh. It will be understood that'before shifting the tumbler unitlongitudinally into alignment with the selected cone gear 62, that it isnecessary to swing lever I35 completely to the left as shown in brokenlines in Figure 2 in order that the tumbler gear 58 is clear of the conegears 62 and the lug I60 out of engagement with the notched rod.

The cone gear selection is made by rotating selector IEI in theappropriate direction. The selector is secured by a set screw I62 to ashaft I63 which is loosely journalled in the sleeve I4I of the gear I42(Figure 8). By this arrangement, the selector IBI may be movedindependently of the lever I35. The outer end of the selector I6Iincludes a pair of knobs I65-I65 to provide a convenient hand hold. Uponthe inner end of shaft IE3 is keyed a gear I36 meshing with an idler I37which in turn meshes with a rack I68. Rack I68 forms a part of a sliderunit I69 (Figure 5) mounted upon slide rods I'm-I10. As shown in Figures5 and 9, the slider includes a bifurcated yoke I'III engaging theopposite sides of the tumbler unit 51 at the pivoted end of the tumblerto prevent binding of the tumbler on its shaft 54. It will be apparenttherefore, that rotation of the selector IIiI will shift the tumblerunit longitudinally relative to the cone gears 62, while the lever I35is held in its left hand limit of travel to hold the tumbler out ofmeshing engagement with the cone gears.

After the selection is made, lever I35 is swung toward the right untilthe tumbler gear 58 meshes with its selected cone gear 62 at which pointthe plunger I38 drops into engagement with the appropriate apertures I31and lug I60 engages a notch of rod I59. The selector IBi includes a hubI72 which is preferably graduated to indicate the several speeds andincludes a series of detent notches Il3 engageable by spring presseddetent I'M (Figure 8) to latch the selector at the desired position.From the foregoing, it will be observed that the gear teeth I37 of thetumbler unit remains constantly in mesh with the elongated. teeth, withthe shaft I48 when the tumbler is shifted longitudinally. By thisarrangement, a smooth, easily controlled connection is maintainedbetween the selectors I35 and IGI and tumbler 5'? to provide quick andaccurate speed changes.

In the present disclosure the cone 63 provides ten speed changes. Byoperation of the range control levers 8t and 9!, these changes aremultiplied by six to provide sixty feed rod and lead screw speedchanges. In order to facilitate gear shifting, the apparatus preferablyincludes a dial plate generally indicated at I'IS. This plate indicatesthe proper positioning of the levers 80, 9|, I35 and I6! to obtain theproper feed rate for the various threads so that the indications of therespective dials are properly correlated and the levers may quickly andconveniently be set. These speeds provide carriage travel either inthousandths of an inch or in millimeters as determined by the conversionmechanism so that the apparatus may quickly be set up for the properoperation.

Having described my invention, I claim:

1. In a feed box for a lathe carriage or the like having shiftable gearsadapted to provide a series of speed ranges, a pair of parallel shafts,selective means for driving one of said shafts, a cone of gears fixed onone of said shafts, a slidable tumbler gear unit pivotally mounted uponthe other of said shafts, and having a gear splined to said shaft, alever having a rotative connection with said tumbler gear for swingingthe same into and out of mesh with the respective gears of the cone, aknob disposed adjacent to the lever and mounted upon a common axistherewith, a gear train in connection with said knob, a rod having arack meshing with said gear train, a slider on said rod and a shifterfork mounted on said slider and engaged with said tumbler gear unit forshifting the tumbler unit longitudinally relative to said cone of gearswhen said knob is rotated.

2. In a feed box transmission for a lathe or the like having shiftablegears adapted to provide a series of speed ranges, a pair of parallelshafts, driving means connected to one of said shafts, a cone of gearsfixed to one of said shafts, a tumbler gear unit slidably mounted on theother of said shafts in driving connection therewith and adapted topivot relative to the shaft to mesh with the respective gears of saidcone of gears, an actuating shaft having continuous gear teeth runninglengthwise thereof and parallel with said tumbler gear mounting shaft, aseries of gear teeth formed in the swinging end of said tumbler gearunit, said teeth being in mesh with the teeth of said shaft to swingsaid tumbler gear unit in an are relative to said cone of gears, anactuating handle including a gear train connected to said actuatingshaft for controlling the swinging movements of said tumbler gear unit,a selector knob mounted on the axis of said actuating lever andincluding a train of gears, a yoke engaging the swinging end of saidtumbler gear unit adjacent to its mounting shaft, and connecting meansextending from said yoke to the gear train of said selector knoboperable to shift said tumbler gear unit longitudinally relative to saidcone of gears when said selector knob is rotated.

3. In a transmission having shiftable gears adapted to provide a seriesof speed ranges, a pair of parallel shafts, driving means connected toone of said shafts, a series of gears fixed to one of said shafts, atumbler gear unit mounted in a substantially balanced upright positionhaving its lower end slidably mounted on the other of said shafts indriving connection there with and adapted to pivot relative to saidshaft. gear teeth formed in the upper swinging end of said tumbler gearunit, an elongated gear coextensive with said series of gears in meshwith the teeth of the tumbler gear unit to establish a slidable drivingengagement therewith, a pivotally mounted control member, a gear trainextending from the control member to said elongated gear operable torotate the elongated gear and thereby swing said tumbler unit into andout of mesh with the respective gears of said series, a second controlmember for shifting the tumbler unit longitudinally relative to saidgears, the second control member being mounted for rotation upon thepivotal axis of the first mentioned control member, a gear train indriving connection with said second control member, a yoke for shiftingsaid tumbler gear unit, said yoke having a bifurcated end in engagementwith the tumbler gear unit at an end opposite to the swinging endthereof and closely adjacent to the mounting shaft, and a rack connectedto said yoke and in mesh with the gear train of said second controlmember to shift the yoke and tumbler gear unit longitudinally relativeto said series of gears to mesh with a selected gear of the cone uponrotation of said second control member.

WILLIAM G. HOELSCHER.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 1,019,798 Kearney et a1. Mar. 12, 1912 1,285,399 Runge Nov.19, 1918 1,422,098 Greenleaf et a1 July 11, 1922 1,628,598 Bird May 10,1927 1,732,561 Kearney et a1 Oct. 22, 1929 1,982,612 Hoelscher Nov. 27,1934 2,199,834 Groene et al May 7, 1949 2,274,958 Hautsch Mar. 3, 19422,447,317 Davenport Aug. 17, 1948 FOREIGN PATENTS Number Country Date236,640 Switzerland Feb. 28, 1945

